Often, electronic devices are cooled by natural or forced air convection. Cooling via air convection may be referred to as single-phase cooling. Unfortunately, because of poor thermal capacitance and heat transfer coefficients of air, and because air convection requires moving large volumes of air past the electronic devices or past heat sinks attached to the electronic devices, this method is not desirable for high power applications, such as radio frequency (RF) applications. Moreover, when large heat sinks are utilized, the overall weight and size of electronic equipment may be adversely increased.
One method proposed to overcome the problems of electronic device cooling associated with air convection suggests the use of evaporative spray cooling. Evaporative spray cooling provides a method for heat removal via evaporation of a cooling liquid from an active surface of a semiconductor die. Evaporative spray cooling may be classified as a two-phase cooling method because of its inherent characteristic conversion of a liquid to a gas. Unfortunately, spray cooling some electronic devices may not be desirable or practical. For example, in typical high-power microwave and RF transistors, the characteristic use of wire interconnects presents significant practical application, performance, assembly handling, and manufacturing liabilities when exposed to spray cooling. In addition, liquids generally used for evaporative spray cooling, may cause a change in the dielectric constant of the space surrounding the electronic device and subsequently de-tune the electronic device, causing it to fail.
There is therefore a need for an electronic device which enables two phase cooling, eliminates the need for wire bonding, allows iterative real-time tuning, and which may be used in high powered applications such as RF assemblies.